Hi Andrew, I am using custom board which uses Analog Device's Blackfin Processor BF527. The OS running is the uClinux provided by the blackfin guys :
http://blackfin.uclinux.org/gf/ <http://blackfin.uclinux.org/gf/>The musb controller driver with the distribution does not support high bandwidth transfer. So, now I tried to modify the ISOC_PACKET_SIZE in the logitech quickcam messenger driver, and brought it down to 64. VGA still didn't work with YUV. Also, I tried to capture a still image at 1 frame per second ( VGA + YUV) . Still no success. Regards, Shekhar On Fri, May 27, 2011 at 6:17 AM, Andrew Leech <coronasen...@gmail.com>wrote: > On 26/05/2011 6:11 PM, Chandrashekhar Lavania wrote: > >> Hi, >> >> I am using linux kernel 2.6.34. I needed to capture VGA frames in YUV >> format with my Logitech E3500 camera. When I try to do that then I get the >> following error:: >> >> uvcvideo: Failed to submit URB 0 (-90). >> VIDIOC_STREAMON: Message too long >> >> This is apparently because the musb does not support high bandwith >> transfer. >> >> >> Hence I was trying to reduce the max packet size for ISO transfer. Any >> idea how this can be done. >> >> I tried to limit the wMaxPacketSize in the uvc_parse_control of >> uvc_deriver.c file, but it did not work. >> >> >> > The host does not have any control over packet size with uvc, this is > decided entirely by the device, this is why gadget has these settings, > gadget is a device driver, not a host driver. > > The only control a host can have is it can request/limit total bandwidth, > but this is only if the device is set up to allow this, for example some > devices will have different bandwidth configurations that it can switch > between if the host gives a bandwidth limit. > For YUV (uncompressed) however the bandwidth is tied directly to the frame > size & rate, so there's no way to change bandwidth without compromising on > frame rate or size, and again these can only be set to settings that the > camera explicitly supports. Even then, for each setting, the packet size is > still up to the camera, there's a good chance at lower bandwidths it'll > still send the same size packets, just doing it less often. > > What hardware are you using for the host? I would look at why it's not > supporting the high bandwidth transfer? > > Andrew > _______________________________________________ > Linux-uvc-devel mailing list > Linux-uvc-devel@lists.berlios.de > https://lists.berlios.de/mailman/listinfo/linux-uvc-devel >
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